Perceptual Grouping and Distance Estimates in Typical and Atypical Development: Comparing Performance across Perception, Drawing and Construction Tasks

Perceptual grouping is a pre-attentive process which serves to group local elements into global wholes, based on shared properties. One effect of perceptual grouping is to distort the ability to estimate the distance between two elements. In this study, biases in distance estimates, caused by four types of perceptual grouping, were measured across three tasks, a perception, a drawing and a construction task in both typical development (TD; Experiment 1) and in individuals with Williams syndrome (WS; Experiment 2). In Experiment 1, perceptual grouping distorted distance estimates across all three tasks. Interestingly, the effect of grouping by luminance was in the opposite direction to the effects of the remaining grouping types. We relate this to differences in the ability to inhibit perceptual grouping effects on distance estimates. Additive distorting influences were also observed in the drawing and the construction task, which are explained in terms of the points of reference employed in each task. Experiment 2 demonstrated that the above distortion effects are also observed in WS. Given the known deficit in the ability to use perceptual grouping in WS, this suggests a dissociation between the pre-attentive influence of and the attentive deployment of perceptual grouping in WS. The typical distortion in relation to drawing and construction points towards the presence of some typical location coding strategies in WS. The performance of the WS group differed from the TD participants on two counts. First, the pattern of overall distance estimates (averaged across interior and exterior distances) across the four perceptual grouping types, differed between groups. Second, the distorting influence of perceptual grouping was strongest for grouping by shape similarity in WS, which contrasts to a strength in grouping by proximity observed in the TD participants

Closure of the Monte Carlo dynamical equation in the spherical Sherrington-Kirkpatrick model

We study the analytical solution of the Monte Carlo dynamics in the spherical Sherrington-Kirkpatrick model using the technique of the generating function. Explicit solutions for one-time observables (like the energy) and two-time observables (like the correlation and response function) are obtained. We show that the crucial quantity which governs the dynamics is the acceptance rate. At zero temperature, an adiabatic approximation reveals that the relaxational behavior of the model corresponds to that of a single harmonic oscillator with an effective renormalized mass

The Kuramoto model: A simple paradigm for synchronization phenomena

Synchronization phenomena in large populations of interacting elements are the subject of intense research efforts in physical, biological, chemical, and social systems. A successful approach to the problem of synchronization consists of modeling each member of the population as a phase oscillator. In this review, synchronization is analyzed in one of the most representative models of coupled phase oscillators, the Kuramoto model. A rigorous mathematical treatment, specific numerical methods, and many variations and extensions of the original model that have appeared in the last few years are presented. Relevant applications of the model in different contexts are also included

The development of spatial category representations from 4 to 7 years

Representation of spatial categories was assessed in 4- to 7-year-olds. Across nine spatial categories (In, On, Under, In Front, Behind, Above, Below, Left, and Right), children were asked to pick the odd-one-out from four images, three of which displayed the same spatial relationship between two objects, and one which showed a different spatial relationship. Results support our proposed model of spatial category representation. Children progressed through three levels of understanding: from rigid (level 1), to abstract (level 2) to broad (including non-prototypical category exemplars) (level 3) understanding of spatial category membership. This developmental pattern was common to all spatial categories, and the ages at which children reached each level varied across categories, in line with the order in which category representations emerge in infancy

Understanding strategic information use during emotional expression judgments in Williams syndrome

Detailed analysis of expression judgments in Williams syndrome reveals that successful emotion categorization need not reflect ‘classic’ information processing strategies. These individuals draw upon a distinct set of featural details to identify happy and fearful faces that differ from those used by typically developing comparison groups: children and adults. The diagnostic visual information is also notably less interlinked in Williams syndrome, consistent with reports of diminished processing of configural information during face identity judgments. These results prompt reconsideration of typical models of face expertise by revealing that an age-appropriate profile of expression performance can be achieved via alternative routes

Distinct profiles of information-use characterize identity judgments in children and low-expertise adults

Face processing abilities vary across the lifespan: increasing across childhood and adolescence, peaking around 30 years of age, and then declining. Despite extensive investigation, researchers have yet to identify qualitative changes in face processing during development that can account for the observed improvements on laboratory tests. The current study constituted the first detailed characterization of face processing strategies in a large group of typically developing children and adults (N=200) using a novel adaptation of the Bubbles reverse correlation technique (Gosselin & Schyns, 2001). Resultant classification images reveal a compelling age-related shift in strategic information-use during participants’ judgments of face identity. This shift suggests a move from an early reliance upon high spatial frequency details around the mouth, eye-brow and jaw-line in young children (~8yrs) to an increasingly more interlinked approach, focused upon the eye region and the center of the face in older children (~11yrs) and adults. Moreover, we reveal that the early vs. late phases of this developmental trajectory correspond with the profiles of information-use observed in weak vs. strong adult face processors. Together, these results provide intriguing new evidence for an important functional role for strategic information-use in the development of face expertise

Concerning the Calculation of Trussed-Beams

For a single-strut trussed-beam, a comparative analysis of the internal forces' values are obtained by two methods. Initially, it is calculated as a single structure using the 'Force Method' (FM). Secondly, a separate calculation of its parts is carried out. The stiffness (main) beam is calculated as a continuous beam, whereas the struts – as a truss. It is shown that the separate calculation of the trussed-beams, can lead to errors in determining the internal forces associated with the assigned dimensions of the stiffness beam's and the pillar elements' crosssections. The comparative analysis of internal forces' values is carried out using the software MathCAD

Developmental changes in the processing of faces as revealed by EEG decoding

Rapidly and accurately processing information from faces is a critical human function that is known to improve with developmental age. Understanding the underlying drivers of this improvement remains a contentious question, with debate continuing as to the presence of early vs. late maturation of face-processing mechanisms. Recent behavioural evidence suggests an important ‘hallmark’ of expert face processing – the face inversion effect – is present in very young children, yet neural support for this remains unclear. To address this, we conducted a detailed investigation of the neural dynamics of face processing in children spanning a range of ages (6 – 11 years) and adults. Uniquely, we applied multivariate pattern analysis (MVPA) to the electroencephalogram signal (EEG) to test for the presence of a distinct neural profile associated with canonical upright faces when compared both to other objects (houses) and to inverted faces. Results revealed robust discrimination profiles, at the individual level, of differentiated neural activity associated with broad face categorization and further with its expert processing, as indexed by the face inversion effect, from the youngest ages tested. This result is consistent with an early functional maturation of broad face processing mechanisms. Yet, clear quantitative differences between the response profile of children and adults is suggestive of age-related refinement of this system with developing face and general expertise. Standard ERP analysis also provides some support for qualitative differences in the neural response to inverted faces in children in contrast to adults. This neural profile is in line with recent behavioural studies that have reported impressively expert early face abilities during childhood, while also providing novel evidence of the ongoing neural specialisation between child and adulthood

Concerning the Question of Calculating a Beam with a Hinge-Rod Chain

We consider the calculation of a statically indeterminate combined system consisting of a beam and a hinge-rod chain of a general form for the action of an arbitrary vertical load. The qualitative regularities of the internal forces in the rods of the hinge-rod chain are established. Depending on the scheme of interaction of the chain with the beam, the calculation of combined systems with and without a horizontal reaction support is considered. Finite formulas are obtained for determining the internal forces in such systems